Wire drawing apparatus



Sept. 24, 1968 P. R. LATHOM WIRE DRAWING APPARATUS Filed March 17, 1966 United States Patent 3,402,589 WIRE DRAWING APPARATUS Paul R. Lathorn, Rockford, Ill., assignor to Fastener Engineers, Inc., Rockford, 111., a corporation of Illinois Filed Mar. 17, 1966, Ser. No. 535,120 12 Claims. (Cl. 72289) ABSTRACT OF THE DISCLOSURE A wire drawing apparatus in which an intermediate section of a continuous length of wire is coiled around a rotary Wire drawing drum for pulling the wire through a wire drawing die. The drum has an annular wire engaging surface to receive the coil of wire and which wire engaging surface has an inlet portion at the inlet end of the coil with a diameter smaller than the outlet portion of the wire engaging surface, the inlet portion of the wire engaging surface flaring outwardly and merging with the relatively larger diameter outlet portion of the wire engaging surface to progressively enlarge the diameter of the wraps of wire as they move axially along the wire engaging surface from the reduced diameter inlet portion onto the outlet portion.

This invention relates to wire drawing method and apparatus.

Wire drawing apparatus have heretofore been made which employ a drum for pulling the wire through the wire drawing die. The wire is wrapped a number of turns around the drum such that, when tension is applied to the wire leaving the drum, the coil of wire is drawn tightly around the drum and provides traction between the drum and the coil to thereby drive the coil with the drum. When the tension on the wire leaving the drum is released, the coil loosens on the drum and the drum then slips inside the coil.

The tension which must be applied to the wire leaving the drum increases markedly with increases in wire size and hardness or tensile strength of the wire. This is due in part to the increase in the draw box pull, that is the tractive force that must be exerted by the drum on the wire to pull it through the die. This force is approximately equal to the area of reduction of the wire times the tensile strength of the wire and often exceeds 3000 pounds. In addition, the tendency of the wire to uncoil or loosen from the drum also increases with increased wire size and/ or tensile strength.

In order to increase the tractive force between the drum and the coil and to overcome the tendency of large or high tensile strength wire to uncoil from the drum, it has heretofore been necessary to increase the tension which is maintained on the wire as it leaves the drum. However, the wire leaving the wire drawing apparatus often passes to another machine having a feed mechanism such as feed rolls for withdrawing the wire and feeding the same to the subsequent machine. Such feed mechanism generally can apply only a limited tension on the wire and, in some applications, it has been found that tension which had to be applied to the wire leaving the drum to maintain the coil tightly on the drum, exceeded the capacity of the feed mechanism and resulted in improper feeding of the Wire to the subsequent machine. This was particularly apparent in connection with high speed machines wherein the wire leaving the wire drawing apparatus was intermittently pulled by the feed mechanism of the subsequent machine at a high rate of speed.

An important object of this invention is to provide a wire drawing method and apparatus which is adapted to handle large diameter and high tensile strength wires.

Another object of this invention is to provide a wire drawing method and apparatus which is adapted for use with machines which intermittently withdraw the wire and which operate at high speeds.

A more particular object of this invention is to provide a wire drawing apparatus having an improved wire drawing drum which reduces the tension required on the wire leaving the drum to maintain traction between the coil and the drum.

Still another object of this invention is to provide a wire drawing apparatus having improved traction between the drum and intermediate wraps of wire on the drum to minimize uneven wear on the drum.

An important feature of the present invention resides in the provision of a wire drawing apparatus having a contoured wire drawing drum including an annular outlet portion and a recess annular inlet portion, wherein the wire is wound on the drum at the inlet portion and is moved axially from the inlet portion onto the larger diameter outlet portion.

These, together with other objects, advantages and features of the present invention will be more readily understood by reference to the following detailed description, when taken in connection with the accompanying draw- 1ngs:

FIGURE 1 is a perspective view of the wire drawing apparatus embodying the present invention;

FIG. 2 is a fragmentary plan view of the wire drawing apparatus and drum;

FIG. 3 is a fragmentary sectional view through the wire drawing drum on a larger scale than FIGS. 1 and 2; and

FIG. 4 is a fragmentary sectional view through a modified form of drum.

The wire drawing apparatus in general includes a support base 10, a wire drawing drum 11 mounted for rotation on the base, a drum drive apparatus 12 operatively connected to the drum to drive the same, and a wire drawing die 13. The wire drawing drum 11 is preferably mounted for rotation in a vertical plane as shown in FIG. 1, it being understood that the drum could be otherwise mounted, for example mounted for rotation in a horizontal plane, if desired. In the embodiment shown, the drum is supported on a drive shaft 14 forming the output of the speed reducer 15, and the shaft 14 is driven from a motor 16 through a variable speed drive mechanism 17, of conventional construction. As is well known in the art, the variable speed drive is adjustable so that the peripheral speed of the drum slightly exceeds the average speed at which wire is to be withdrawn'from the wire drawing apparatus. The wire drawing die 13 is supported adjacent one side of the periphery of the drum and, in the form shown, is mounted on a pedestal 21 attached to the base. The die 13 is conveniently mounted in a draw box or lubricant box 22 having a compartment 23 for receiving lubricant and the like, and the draw box is preferably supported for swinging movement so as to allow automatic alignment of the drawing die with wire winding on the drum. As shown, the box is privotally supported on the pin 24 at the upper end of the post for horizontal swinging movement at a level such that the die axis is generally tangent to the drum. The die 13 may be of any conventional construction having a tapered draw opening 13a therein, and the draw box has a second opening 23a at the other end of the lubricant chamber 23 to allow the wire to pass through the lubricant chamber and through the die. The wire, after passing through the die 13, is wrapped a number of times around the drum 11 to form an intermediate coil. As used herein, the term intermediate coil refers to the coil on the drum which is formed intermediate the ends of the wire and wherein the wire continuously winds onto one end of the coil while unwinding from the other end of the coil so that the number of loops or wraps in the coil remains constant while the drum is in operation, but wherein the wire which forms the coil is continuously changing.

The wire, after it unwraps from the drum, is passed to a succeeding apparatus hereinafter generally referred to as a production machine, and which may include a machine that cuts or otherwise utilizes the wire in forming items; a wire straightening machine; a further Wire drawing machine or a wire rewinding apparatus. The subsequent production machines customarily have a feed mechanism associated therewith which withdraws the wire from the wire drawing apparatus and feeds it to the subsequent machine. A feed mechanism is diagrammatically indicaed at 31 in FIG. 1 and, as shown, includes grooved feed rolls 32 which grip the wire therebetween and which are driven to feed the drawn wire from the drawing machine to the subsequent production machine. Any conventional mechanism may be provided for driving the feed rolls and for maintaining the feed rolls in tight engagement with the wire and the feed rolls may be intermittently or continuously driven depending upon the type of production machine.

In a wire drawing apparatus of this type, the variable speed drive mechanism is adjusted so as to rotate the drum at a speed which is at least equal to and preferably slightly greater than the average rate at which the feed mechanism 31 of the subsequent production machine withdraws the wires so that the drum will pull the wire through the die at a rate at least equal to the rate at which it is consumed by the production machine. The drum drives the coil of wire only when the coil is maintained sufliciently tightly around the drum to provide enough traction between the drum and the coil to overcome the drawbox pull. In order to progressively increase and decrease the tension on the outlet wrap of the wire in the coil, and hence progressively change the traction between the drum and the coil, it is common practice to employ a wire tensioning apparatus such as an idler roll 35 which engages a loop of wire designated L after it leaves the drum, and which idler roll is yieldably urged in a direction to take up the slack in the loop. The machine illustrated herein is of the inline type wherein the wire enters from one side of the drum, wraps around the drum a preselected number of turns, and then leaves the wire drawing apparatus traveling in the same general direction as it enters the wire drawing apparatus. The idler roll 35 is disposed at the side of the drum opposite the feed rolls 31 and is supported as by an arm 36 for movement toward and away from the periphery of the drum. The arm is conveniently supported for swinging movement on a shaft 36a and the idler roll is yieldably urged in the direction away from the drum by any suiiable mechanism which will apply a force on the idler roll that varies through a preselected range from a minimum when the idler roll is remote from the drum to a maximum when the idler roll is adjacent the drum. In the embodiment shown, the idler roll biasing means is in the form of springs 37 attached to the arm and to the pedestal 21, it being understood that other means such as a pneumatic cylinder could be employed if desired. As will be seen, the tension applied by the idler roll to the wire leaving the drum increases as the slack in the loop L decreases, and this decreases the slip between the drum and the coil to pull the wire through the die. Conversely, if the subsequent production machine is not withdrawing wire as fast as it is being advanced by the drum, the loop L of wire will enlarge and the tension on the last wrap of wire on the drum will decrease to allow increased slipping between the drum and the coil. The force range of the idler roll biasing means is preferably made adjustable as by changing the number or size of the springs 37 or by shifting of the spring anchor 38 to change the tension on the springs when the loop is slack.

The draw box pull, that is the force required to pull the wires through the die, in general increases with increasing wire size and/or tensile strength of the wire. 75

Greater traction between the drum and the coil is therefore required to overcome the draw box pull and this, in turn, requires that the coil be drawn more tightly around the drum to achieve the greater traction. However, as the wire increases in size and/ or tensile strength, there is an increased tendency of the wire to loosen or uncoil from the drum and this, in turn, has heretofore required application of a greater tension on the wire as it unwraps from the drum.

It has been found that the tension which must be applied to the wire as it leaves the drum can be markedly reduced for any given size and tensile strength of wire or, alternatively, that larger and higher tensile strength wires can be drawn on a drum of a given size without increasing the tension requirements on the Wire as it leaves the drum, if the drive surface of the drum is formed with an annular depressed inlet portion in the area adjacent where the wire initially wraps on the drum. A preferred contour for the Wire drawing drum is best shown in fragmentary cross-sectional view of FIG. 3. As shown therein, the drum has a wide annular wire engaging surface designated generally by the numeral 50, and which wire engaging surface has an overall width greater than the axial width of the coil and sufficient to receive at least 6 to 8 wraps of wire and preferably a greater number such as 9-12 wraps of the largest diameter wire to be drawn by the machine. The drum has an inlet flange 51 at one end which is arranged to engage the wire as it wraps on the drum and, preferably, an outlet flange 52 at the other end of the wire engaging surface. The wire engaging surface 50 extends between the flanges and includes a generally cylindrical outlet portion designated 50 and which extends axially between the points designated a and c in FIG. 3, and an annular depressed inlet portion designated 50", and which extends between the point a where the inlet portion merges with the cylindrical outlet portion, and the point designated b where the depressed inlet portion 50" enlarges to the diameter of the outlet portion and merges with the inlet flange 51. The inlet portion 50" preferably merges in a smooth continuous curve with the inclined inner face 51' of the inlet flange, as is clearly shown in FIG. 3, and the inlet portion 50 of the wire engaging surface is herein defined as that portion of the wire engaging surface which is recessed below the diameter of the outlet portion 51'.

The inlet portion is shaped to form a wide shallow depression and has a width suflicient to receive at least several and preferably 3 or 4 wraps of the largest wire to be drawn on the drum, while the depth of the depression is very small as compared to the width and less than the diameter of the largest wire to be drawn on the wire drawing apparatus. It has been found preferable to form the depressed inlet portion 50" with a cross-section in which the point indicated at e constituting the minor diameter of the inlet portion is substantially closer to the flange 51 than to the outlet portion. For reasons pointed out hereinafter, the point e of minor diameter of the inlet portion is spaced axially a distance at least several times the depth of the depression from the point a where the inlet portion merges with the outlet portion, and the inlet portion is shaped to flare outwardly at a shallow angle from its minor diameter toward the outlet portion to gradually expand the diameter of the wraps of wire as they are moved axially along the drum from the inlet portion. In practice, the same wire drawing drum is frequently used for drawing wires having sizes which vary over a relatively wide range. The depth of the recessed inlet portion is accordingly preferably selected to accommodate a range of wire sizes and for this purpose is advantageously made about one-half the diameter of the largest size wire to be drawn, so as to thereby enable use of the drum for smaller size wires. For example, in a wire drum for use with wire sizes from about V to /1" groove depth is preferably made of the order of Ms to 4s" in depth, it being understood that a greater groove depth is preferred for larger size wire, particularly if the wire material is of material having a high tensile strength.

The wire w after it passes through the drawing die 13 wraps on the drum between the inlet flange 51 and the previous wraps of wire on the drum. In the coil shown in section in FIG. 3, the coil comprises 8 wraps of wire designated wl-wS inclusive, it being understood that a greater or lesser number of wraps may be employed. The inlet Wrap designated wl winds on the coil between the inclined innerface 51' of the inlet flange and the preceding wrap W2 and the tension on the inlet wrap due to the high draw box pull, tends to pull the inlet wrap toward the minor diameter of the inlet portion. In practice, the position. of the inlet wrap of wire wl will shift somewhat between a position at the minor diameter e and a position offset from the minor diameter toward the inlet flange under different operating conditions and dependent on the resistance of the coil to axial movement along the drum. Thus, with the depressed inlet portion 50' in the wire engaging surface, the wraps of wire will initially wind on the drum adjacent its minor diameter and the wraps are then progressively expanded as they move from the minor diameter e toward the generally cylindrical outlet portion 50. This arrangement has been found to markedly improve the traction between the coil and the drum and the improved operation is thought to be attributable to several factors.

At the outset it is to be noted that the tension in the wraps of wire decreases in a direction from the inlet end to the outlet end, with the tension and hence the pressure between each wrap and the drum being a maximum at the inlet end and a minimum at the outlet end of the coil. Heretofore, this high tension and pressure between the inlet wrap and the drum has tended to cause excessive wear on the drum at the point corresponding to the inlet wrap or, alternatively, pick upor depositing of metal from the wire on the drum in, this region. It is believed that, with the depressed inlet portion 50" on the wire engaging surface, the wraps in the depressed inlet portion tend to be held more tightly against the drug surface by adjacent wire wraps at a larger diameter. Thus, in the form shown in FIG. 3, the Wrap w2 being on a slightly larger diameter than w, exerts a force on that wrap having a component normal to the drum surface and which tends to press the initial wrap w1 toward the base of the depressed inlet portion and, similarly, the wraps W3, W4 tend to respectively press the Wraps W2 and W3 downwardly toward the base or minor diameter of the inlet portion of the wire engaging surface. It is considered that this tends to increase the pressure between the wraps in the inlet portion of the drum and the surface of the drum and thus improves traction between the drum and coil.

In addition to the above, it is to be noted that the wraps of wire, as they wrap on the drum, are pulled to a relatively smaller diameter corresponding to the minor diameter of the inlet portion and indicated at e in FIG. 3. Then, as the wire wraps move axially along the drum from the minor diameter toward the outlet portion 50', the diameter of each wrap must progressively increase. It is considered that the pulling of each of the wraps of wire to a diameter somewhat smaller than the diameter of the outlet portion reduces the tendency of the wraps to uncoil to a diameter substantially above the diameter of the outlet portion, when tension on the outlet end of the coil is released. Stated otherwise, the outlet portion, having a larger pitch diameter than the minor diameter of the inlet portion, more nearly conforms to the diameter of the coils when they are loosened so that less tension is required on the outlet wrap to maintain the outlet wrap in tight engagement with the generally cylindrical oulet surface 50'.

There is, in addition to the above, a circumferential movement of the wraps of wire which can be noted as they move along the depressed inlet portion and onto the outlet portion. Thus, if a mark indicated at the point m is made on the inlet end of the drum and, if a mark is made on each wrap of wire in alignment with the Wire m, when that wire wrap initially wraps on the drum, there will be a shifting of these marks as the wire wraps move axially along the drum. The points designated m8-m1 represent marks made on the successive wraps as they wind on the drum. The marks on the successive wraps tend to shift relative to the mark on the drum in a direction opposite the direction of rotation of the drum due in part to the slip between the initial wrap and the drum. Stated otherwise, the wire drawing drum is operated at a speed to feed wire slightly faster than it is consumed by the subsequent production machine, and this allows the coil to loosen periodically suflicient to permit some slip between the drum and the coil. Therefore, as the drum turns through one revoltuion, the length of the initial wrap will be less than the circumference of the drum at the point where the wire wraps on the drum by an amount corresponding to the slip between the drum and the initial wrap of wire. Thus, the mark on each wrap will shift in a direction opposite the direction of rotation of the drum with respect to the mark on the next succeeding wrap due to this slip bet-ween the wire and the drum as the wire initially wraps on the drum. In addition, as the wraps move out of the minor diameter of the inlet portion, the coils increase in diameter and this causes a further slipping of the wraps relative to the succeeding wraps and relative to the drum. As shown in FIG. 2, the marks m2-m8 are shifted progressively greater distances relative to the mark in on the drum due to the combined slippage between the initial wrap on the drum and the change in diameter of the wraps as they move from the depressed inlet portion of the drum onto the generally cylindrical outlet portion. As the wraps increase in diameter during movement from the depressed inlet portion onto the outlet portion, there is also a relative sliding movement between adjacent wraps. Substantial lateral pressure exists between adjacent wraps on the drum and it is considered that this circumferential movement of adjacent wraps of wire on the drum may also have an effect in tightening the coil on the drum and improving the traction between drum and the intermediate wraps of the coil. It is further to be noted that, by reason of the larger diameter of the outlet portion relative to the inlet portion, the peripheral speed of the outlet portion of the drum is slightly higher than that of the inlet portion.

The wire drawing drum rim illustrated in FIG. 4 is similar to that shown in FIG. 1 but has a slightly modified inlet portion. As in the preceding embodiment, the rim has an annular drive surface 156 including a generally cylindrical outlet portion and a recessed inlet portion 150" with a flange 151 at the inlet end. The inlet portion extends between points a and b and is recessed below the level of the outlet portion 150' to a maximum depth d. The area of maximum depth or minor diameter e is located relatively closer to the flange 151 than to the outlet portion and the recessed inlet portion preferably merges in a smooth curve with the inner face 151' of the flange. In this embodiment, the recessed inlet portion flares outwardly with a generally uniform taper to the outlet portion and merges smoothly therewith. The maximum depth d of the recessed portion is herein shown of the same general magnitude as in the previous embodiment, but the wire size illustrated is somewhat smaller than that shown in the previous embodiment to illustrate the use of the drum in connection with smaller size wires of the order of A" in diameter.

From the foregoing it is thought that the construction and operation of the apparatus will be readily understood. The wire drawing drum is driven at a speed slightly in excess of the speed in which the feed mech anism 31 withdraws and advances the wire to the sub sequent production machine. As the slack loop indicated at L decreases, the tension exerted by the compensator arm and roller 35 increases and this increases the tension on the outlet wrap wS. Since the spring tension on the idler roll progressively increases, the tension on the last wrap of wire is also progressively increased to provide a progressive decrease in the slip between the drum and the coil. Conversely, when the loop indicated at L becomes slack, the pressure exerted by the springs 37 also decreasesand this relaxes the tension on the outlet wrap to allow the drum to slip inside the coil.

The wraps of wire as they wind on the drum are drawn through a smaller diameter indicated at the minor diameter point e of the inlet portion, and then are progressively expanded as they move from the minor diameter onto the generally cylindrical outlet portion of the drum. The diameter of the outlet portion 50', While less than the expanded diameter of the wire wraps when the coil is loose, more nearly conforms to the expanded or loose diameter of the coil so that less tension is required on the outlet wrap to maintain the latter in tight engagement with the drum. As in a conventional drum, this tension can be adjusted over a significant range by increasing or decreasing the number of wraps on the outlet portion of the drum.

In practice it has been found that the provision of the depressed inlet portion on the drum enables drawing of larger diameter wires and also wires which have a higher tensile strength for a given drum size, and for any given number of wraps of wire on the drum. Conversely, the contoured drum enables the use of the smaller drum diameter for wire of a particular size or tensile strength than could be used with a conventional cylindrical drum. In general, when the number of wraps of wire used on the contoured drum is the same as that used on a conventional cylindrical drum of like diameter, substantially less tension is required on the outlet wrap of wire on the contoured drum to prevent excessive slippage between the drum and the inlet wrap of wire. Although the slippage between the outlet wraps and the drum is increased with the contoured drum, the tension on the outlet wraps is less than the inlet wrap so that slippage of the outlet wraps does not cause a serious wear problem. Thus, it has been found that high tensile strength wire having approximately a half-inch diameter can be successfully drawn on a 28" drum while requiring only a moderate tension on the wire leaving the drum while a substantially higher tension is required on a conventional drum of like dimensions but without a recessed inlet portion. With the above-mentioned drum, it has been found that a grooved depression having a depth of about A" for the half-inch Wire, produced satisfactory results.

It should be understood that various changes, modifications and alterations may be made in the details of construction without departing from the spirit and scope of the invention as defined in the appended claims. It should be further understood that the invention is not intended to be limited to any particular theory or mode of operation, but is rather intended to encompass all that comes within the appended claims, when read in the light of the foregoing description of the invention.

I claim:

1. A wire drawing drum for a wire drawing machine, said drum having an annular wire engaging surface which is sufliciently wide to receive a coil of wire comprising a plurality of wraps of wire in a single layer, said drum having a flange extending outwardly from a Wire engaging surface at one end of the wire engaging surface for engaging the wire as it wraps on the drum to move the coil axially along the drum toward the other end of the Wire engaging surface, characterized in that the wire engaging surface has an annular outlet portion adjacent said other end and an annular inlet portion, said inlet portion of the wire engaging surface defining shallow annular depression below the diameter of the outlet portion disposed between the flange and the outlet portion and having an axial width which is sufliciently wide to receive a number of wraps of the wire in a single layer, said inlet portion having its minor diameter in an area spaced axially from the outlet portion a distance at least several times the depth of the depression and said inlet portion flaring outwardly from said minor diameter at a shallow angle toward said outlet portion and merging therewith to progressively enlarge the diameter of the wraps of wire as they move axially along the wire engaging surface from the minor diameter of the inlet portion onto said outlet portion.

2. A wire drawing drurn according to claim 1 wherein said annular depression has a cross-section in the form of a smooth concave curve merging at one end with the outlet portion and at the other end with said flange.

3. A wire drawing drum according to claim 1 wherein said minor diameter of said inlet portion is located substantially closer to said flange than to said outlet portion.

4. A wire drawing drum according to claim 2 wherein said annular depression has a cross-section that flares outwardly from said minor diameter in a smooth concave curve to said flange and flares outwardly from said minor diameter in a generally uniform taper to said outlet portion.

5. In a wire drawing apparatus including a wire drawing die; a drum drive apparatus; a wire drawing drum drivingly connected to the drive apparatus, said drum having an annular wire engaging surface receiving an intermediate coil of wire composed of a plurality of wraps of wire in a single layer with an inlet end where the wire wraps on the drum and an outlet end where the wire unwraps from the drum, said drum having a flange extending outwardly from the wire engaging surface at one end thereof for engaging the wire as it wraps on the drum to move the coil axially along the drum toward the other end of the wire engaging surface, the improvement characterized in that the wire engaging surface has a generally cylindrical outlet portion and an inlet portion extending between said flange and said outlet portion, said inlet portion having an axial width suflicient to receive a number of wraps of wire in a single layer wherein the number of wraps is less than said plurality of wraps which comprise the coil on the drum so that the remaining wraps of the coil are wound around said outlet portion, said inlet portion defining an annular depression below the diameter of the outlet portion disposed between the flange and the outlet portion, said inlet portion having its minor diameter in an area spaced axially from said outlet portion at least several times the depth of the depression and said inlet portion flaring outwardly from said minor diameter at a shallow angle toward said outlet portion and merging therewith to progressively enlarge the diameter of the wraps of wire as they move axially along the wire engaging surface from the minor diameter of the inlet portion onto said outlet portion.

6. An apparatus according to claim 5 wherein the maximum depth of the annular depression is less than the diameter of the wire to be drawn.

7. An apparatus according to claim 5' wherein the maximum depth of the annular depression is in the range Ma" to /8.

8. An apparatus according to claim 5 wherein said annular depression has a cross-section in the form of a smooth curve merging at one end with said outlet portion and at the other end with said flange.

9. An apparatus according to claim 5 wherein said minor diameter is located substantially closer to said flange than to said outlet portion.

10. An apparatus according to claim 5 including wire feed means engageable with the wire after it unwraps from the drum, an idler wheel engageable with a slack loop of the wire intermediate the feed means and the drum,

and means yieldably urging the idler wheel in a direction to tension the slack loop of wire and apply a yieldable tension on the last wrap of wire that increases as the slack loop of wire decreases whereby to reduce slipping between the coil and the drum as the slack loop decreases.

11. The method of pulling wire through a wire drawing die comprising, providing a drawing drum having portions of relatively different diameter merging smoothly with each other, forming a coil composed of a number of wraps of wire around the drawing drum, rotating the drum to Wind the wire from the drawing die at an inlet end of the coil onto a reduced diameter portion of the drum while forcing the previous wraps of wire on the drum in a direction axially along the drum onto a portion of larger diameter than said reduced diameter portion to progressively expand the diameter of wraps as they move onto the larger diameter portion of the drum, and unwinding the wire from an outlet end of the coil at the larger diameter of the drum as the wire is wound onto the drum at the inlet end of the coil.

12. The method of claim 11 including the step of maintaining a yieldable tension on the wire as it unwinds from the drum.

References Cited UNITED STATES PATENTS 407,612 7/ 1889 Rawson 72289 827,019 7/1906 Horton 7244 1,675,822 7/1928 Pushalski 724l9 1,918,237 7/1933 Alden 72419 1,963,456 6/1934 Worthington 72289 2,124,967 7/1938 Woodward 72419 2,167,397 7/1939 Tideman 72419 2,717,072 9/1955 Andrews et a1 721289 3,058,681 10/1962 Clarkson 242-4709 CHARLES W. LANHAM, Primary Examiner.

E. M. Combs, Assistant Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.6. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,402,589 September 24 1968 Paul R. Lathom It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 6 beginning with "11 The method of pulling" cancel all to and including the drum." in line 3, of column 10. In the heading to the printed specification, line 7, "12 Claims" should read 10 Claims Signed and sealed this 10th day of February 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr. Attesting Officer 

